High-voltage, three phase recloser assemblies (also referred to as reclosing relays) are used in three phase electric power distribution networks to provide for circuit breaking of electrical power when an overcurrent condition is sensed on any one of the three power transmission lines coupled to the recloser assembly. Typical voltage rating of such recloser assemblies range from 15 kilovolts (kV) to 38 kV and an interrupting current rating of up to 12,600 amps. A controller is electrically coupled to three solenoid actuated switching assemblies of the recloser assembly. When an overcurrent condition on a transmission line is sensed by a controller electrically coupled to the recloser assembly, controller causes the recloser assembly to open the three switching assemblies, each switching assembly being coupled to a different one of the three power lines. Each of the three switching assemblies includes a line terminal and a switch terminal coupled in series with a power transmission line. Tripping or opening a recloser switching assembly causes an open circuit condition between the line and switch terminals and interrupts the supply of power on that power transmission line. After a predetermined time, the controller sends electrical signals to the recloser switching assembly causing the solenoid switch to close and resuming power transmission through the switching assembly. The controller continually monitors for overcurrent conditions on the power transmission lines.
A prior art three phase recloser assembly is shown in FIGS. 1 and 2 at 50. As can be seen in FIG. 2, the recloser assembly 50 is typically mounted on a utility pole 85. A controller monitors currents through the recloser assembly terminals and opens the three recloser switching assemblies when an overcurrent condition is sensed on one or more of the power transmission lines. Typically, current through the terminals is sensed via three current transformers (CTs), one CT positioned coaxial to each of the three line terminals 52, 60, 68. The controller 90 is typically mounted on the pole 85 at a lower height above ground so as to be accessible to a technician standing on the ground. The controller 90 and recloser assembly 50 are electrically coupled by a cable 92. FIG. 1 shows a prior art vacuum type recloser assembly 50 manufactured by Joslyn Hi-Voltage Corporation, Cleveland Ohio 44105, the assignee of the present invention.
The recloser assembly 50 includes a tank 80, at ground potential, and three sets of terminals 52, 56, 60, 64, 68, 72. The first set of terminals 52 (line terminal), 56 (switch terminal) provide for a circuit breaker connection for a first power distribution line (first phase of a three phase distribution network). The second set of terminals 60, 64 provide for a circuit breaker connection for a second power line (second phase of the three phase network) and a the third set of terminals 68, 72 provide for a circuit breaker connection for a third power line (third phase of the three phase network). Air bushings 54, 58, 62, 66, 70, 74 insulate respective terminals 52, 56, 60, 64, 68, 72 from the tank 80. The tank 80 is filled with an dielectric insulating gas such as sulfur hexafluoride, SF.sub.6, or oil and is held at ground potential.
Three vacuum interrupter switch contact assemblies provide the circuit beaker connection between the first set of terminals, the second set of terminals and the third set of terminals. A suitable vacuum interrupter assembly is disclosed in U.S. Pat. No. 5,387,771 to Luehring issued Feb. 7, 1995, entitled "Axial Magnetic Field High Voltage Vacuum Interrupter" and assigned to the assignee of the present invention. U.S. Pat. No. 5,387,771 is incorporated herein in its entirety by reference.
Prior art three phase recloser assemblies were characterized by long assembly times and numerous switching components. Also, use of sulfur hexafluoride, SF.sub.6 as an insulating material in the tank was less than desirable because of environmental concerns. Additionally, the recloser assembly could not easily be changed to accommodate single phase operation.
What is needed is an improved three phase recloser assembly that is more efficient to assemble than current art reclosers and has less switching components. What is also needed is a recloser that uses a more environmentally friendly insulating material. What is also needed is a recloser that can easily be adapted for three phase or single phase operation.